LINEAR TECHNOLOGY LTC4307 Technical data

FEATURES

LTC4307

Low Offset Hot Swappable

2-Wire Bus Buffer with Stuck

Bus Recovery

U

DESCRIPTIO

■

Bidirectional Buffer with Stuck Bus Recovery

■

60mV Buffer Offset Independent of Load

■

30ms Stuck Bus Timeout

■

Compatible with Non-Compliant VOL I2C Devices

■

Prevents SDA and SCL Corruption During Live

Board Insertion and Removal from Backplane

■

±5kV Human Body Model ESD Protection

■

Isolates Input SDA and SCL Line from Output

■

Compatible with I2CTM, I2C Fast Mode and SMBus

■

READY Open-Drain Output

■

1V Precharge on All SDA and SCL Lines

■

High Impedance SDA, SCL Pins for VCC = 0V

■

Small 8-Lead (3mm × 3mm) DFN and 8-Lead MSOP

Packages

U

APPLICATIO S

■

Live Board Insertion

■

Servers

■

Capacitance Buffer/Bus Extender

■

RAID Systems

■

ATCA

The LTC®4307 hot swappable, 2-wire bus buffer allows
I/O card insertion into a live backplane without corrup­tion of the data and clock busses. The LTC4307 provides
bidirectional buffering, keeping the backplane and card
capacitances isolated. Low offset and high V

tolerance

OL

allows multiple devices to be cascaded on the clock and
data busses. If SDAOUT or SCLOUT are low for 30ms, the
LTC4307 will automatically break the bus connection. At
this time the LTC4307 automatically generates up to 16
clock pulses on SCLOUT in an attempt to free the bus. A
connection will resume if the stuck bus is cleared.

During insertion, the SDA and SCL lines are pre-charged
to 1V to minimize bus disturbances. When driven high,
the ENABLE input allows the LTC4307 to connect after a
stop bit or bus idle. Driving ENABLE low breaks the con­nection between SDAIN and SDAOUT, SCLIN and SCLOUT.
READY is an open-drain output which indicates that the
backplane and card sides are connected.

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 7032051, 6356140, 6650174

TYPICAL APPLICATIO

3.3V

0.01μF

MICRO-

CONTROLLER

10k 2.7k 10k 10k 0.01μF

10k

ENABLE

SCLIN

SDAIN

V

CC

LTC4307

SCLOUT

SDAOUT

GND

3.3V

10k

READY

U

2.7k

BACKPLANE

CONNECTOR

CARD

CONNECTOR

100k

ENABLE

SCLIN

SDAIN

V

CC

LTC4307

SCLOUT

SDAOUT

GND

CARD

READY

3.3V

4307 TA01a

10k

CARD_SCL

CARD_SDA

Rising Edge from Asserted Low

1000

800

600

LOW

OFFSET

200mV/DIV

400

200

0

SDAOUT

SDAIN

0 100 200 300 400 600500

100ns/DIV

4307 TA01b

4307f

1

LTC4307

WW

W

ABSOLUTE AXI U RATI GS

U

(Notes 1, 7)

VCC to GND ................................................. – 0.3V to 6V

SDAIN, SCLIN, SDAOUT, SCLOUT,

READY, ENABLE .......................................... –0.3V to 6V

Maximum Sink Current (SDAIN, SCLIN, SDAOUT,

SCLOUT, READY) .............................................. 50mA

Operating Temperature Range

LTC4307C ................................................ 0°C to 70°C

LTC4307I ............................................. – 40°C to 85°C

UUW

PACKAGE/ORDER I FOR ATIO

TOP VIEW

1ENABLE

SCLOUT

2

SCLIN

3

GND

4

8-LEAD (3mm × 3mm) PLASTIC DFN

T

EXPOSED PAD (PIN 9) CONNECTION TO GND IS OPTIONAL

JMAX

9

DD PACKAGE

= 125°C, θJA = 43°C/W

8

7

6

5

V

CC

SDAOUT

SDAIN

READY

ORDER PART

NUMBER

LTC4307CDD
LTC4307IDD

DD PART*
MARKING

LBTW
LBTW

Storage Temperature Range

DFN ....................................................– 65°C to 125°C

MSOP ................................................– 65°C to 150°C

Lead Temperature (Soldering, 10 sec)

MSOP ............................................................... 300°C

ORDER PART

NUMBER

ENABLE

1

SCLOUT

2

SCLIN

3

GND

4

8-LEAD PLASTIC MSOP

T

= 125°C, θJA = 200°C/W

JMAX

TOP VIEW

MS8 PACKAGE

8

V

7

SDAOUT

6

SDAIN

5

READY

CC

LTC4307CMS8
LTC4307IMS8

MS8 PART*

MARKING

LTBTV
LTBTV

Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.

The

ELECTRICAL CHARACTERISTICS

● denotes the specifi cations which apply over the full operating

temperature range, otherwise specifi cations are at TA = 25°C. VCC = 3.3V, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Power Supply

V

CC

I

CC

I

SD

V

PRE

t

IDLE

V

THR_ENABLE

I

ENABLE

t

PLH_EN

t

PHL_EN

t

PLH_READY

t

PHL_READY

V

OL_READY

I

OFF_READY

Positive Supply Voltage

Supply Current VCC = 5.5V, V

Shutdown Supply Current VCC = 5.5V, ENABLE = GND, SDA, SCL = 5.5V

Precharge Voltage SDA, SCL Floating

Bus Idle Time

ENABLE Threshold 0.8 1.4 2 V

ENABLE Input Current ENABLE from 0V to V

ENABLE Delay Off-On VCC = 3.3V (Figure 1) 95 μs

ENABLE Delay On-Off VCC = 3.3V (Note 3) (Figure 1) 10 ns

READY Delay Off-On VCC = 3.3V (Note 3) (Figure 1) 10 ns

READY Delay On-Off VCC = 3.3V (Note 3) (Figure 1) 10 ns

READY Output Low Voltage I

READY Off Leakage Current VCC = READY = 5.5V

= 3mA, VCC = 2.3V

PULLUP

SCLOUT

= V

CC

SDAOUT

= 0V (Note 6)

●

2.3 5.5 V

●

●

●

0.8 1 1.2 V

●

55 95 175 μs

●

●

●

811 mA

900 1200 μA

0.1 ±5 μA

0.1 ±5 μA

0.4 V

2

4307f

LTC4307

The ● denotes the specifi cations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifi cations are at T

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

Propagation Delay and Rise-Time Accelerators

t

PHL

t

PLH

t

RISE

t

FALL

I

PULLUPAC

Input-Output Connection

V

OS

V

THR

V

HYS

C

IN

I

LEAK

V

OL

V

ILMAX

Bus Stuck Low Timeout

t

TIMEOUT

Timing Characteristics

f

I2C,MAX

t

BUF

t

HD,STA

t

SU,STA

t

SU,STO

t

HD,DATI

t

SU,DAT

SDA/SCL Propagation Delay High to Low C

SDA/SCL Propagation Delay Low to High C

SDA/SCL Transition Time Low to High C

SDA/SCL Transition Time High to Low C

Transient Boosted Pull-Up Current Positive Transition on SDA, SCL, VCC = 3.3V

Input-Output Offset Voltage 2.7k to VCC on SDA, SCL, VCC = 3.3V,

SDA, SCL Logic Input Threshold Voltage Rising Edge 0.45VCC0.55VCC0.65V

SDA, SCL Logic Input Threshold Voltage
Hysteresis

Digital Input Capacitance SDAIN, SDAOUT,
SCLIN, SCLOUT

Input Leakage Current SDA, SCL, Pins

Output Low Voltage SDA, SCL Pins, I

Buffer Input Logic Low Voltage VCC = 3.3V

Bus Stuck Low Timer VCC = 3.3V, SDAOUT, SCLOUT = 0V

I2C Maximum Operating Frequency (Note 3) 400 600 kHz

Bus Free Time Between Stop and Start
Condition

Hold Time After (Repeated) Start Condition (Note 3) 100 ns

Repeated Start Condition Set-Up Time (Note 3) 0 ns

Stop Condition Set-Up Time (Note 3) 0 ns

Data Hold Time Input (Note 3) 0 ns

Data Set-Up Time (Note 3) 100 ns

= 25°C. VCC = 3.3V, unless otherwise noted.

A

= 50pF, 2.7k to VCC on SDA, SCL,

LOAD

V

= 3.3V (Notes 2, 3) (Figure 1)

CC

= 50pF, 2.7k to VCC on SDA, SCL,

LOAD

V

= 3.3V (Notes 2, 3) (Figure 1)

CC

= 100pF, 10k to VCC on SDA, SCL, VCC

LOAD

70 ns

10 ns

30 300 ns

= 3.3V (See Notes 3, 4) (Figure 1)

= 100pF, 10k to VCC on SDA, SCL, VCC

LOAD

30 300 ns

= 3.3V (See Notes 3, 4) (Figure 1)

58 mA

(Note 5)

●

20 60 100 mV

Driven SDA/SCL = 0.2V

CC

(Note 3) 50 mV

(Note 3) 10 pF

= 4mA,

Driven SDA/SCL = 0.2V, V

SINK

= 2.7V

CC

2.7k to VCC on SDA, SCL, VCC = 3.3V,

●

●

0 0.4 V

●

120 160 205 mV

±5 μA

Driven SDA/SCL = 0.1V

●

●

25 30 35 ms

1.2 V

(Note 3) 1.3 μs

V

Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.

Note 2: See “Propagation Delays” in the Operations section for a
discussion of t

PHL

and t

as a function of pull-up resistance and bus

PLH

capacitance.

Note 3: Determined by design, not tested in production.

Note 4: Measure points are 0.3 • V
Note 5: I

varies with temperature and VCC voltage as shown in the

PULLUP

and 0.7 • VCC.

CC

Typical Performance Characteristics section.
Note 6: I

test performed with connection circuitry active.

CC

Note 7: All currents into pins are positive; all voltages are referenced to
GND unless otherwise specifi ed.

4307f

3

LTC4307

TIMING DIAGRAMS

ENABLE, CONNECT, READY Timing

t

PHL_EN

t

PHL_READY

4307 TD01

ENABLE

CONNECT

READY

t

PLH_READY

t

PLH_EN

Rising and Falling Propagation Delay and Rise and Fall Times for SDAIN, SDAOUT and SCLIN, SCLOUT

SDAIN/SCLIN

SDAOUT/SCLOUT

t

PLH

t

PHLtRISE

t

RISE

t

FALL

t

FALL

4307 TD02

Figure 1. Timing Diagrams

4307f

4

C

V

V

(V)

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LTC4307

TA = 25°C, VCC = 3.3V, unless otherwise indicated.

ICC vs Temperature I

8.3

8.0

7.7

7.4

7.1

(mA)

CC

I

6.8

6.5

6.2

5.9
–50

VCC = 5.5V

VCC = 3.3V

VCC = 2.3V

–25 0 50

25

TEMPERATURE (°C)

75

100

4307 G01

Input-Output High to Low
Propagation Delay vs Temperature

100

VCC = 5.5V

= 50pF

OUT

= R

PULLUPOUT

02550

TEMPERATURE (°C)

VCC = 3.3V

= 10k

(ns)

PHL

t

80

60

40

20

0

VCC = 2.3V

CIN = C
R

PULLUPIN

–50

–25

20

16

12

(mA)

8

PULLUPAC

I

4

0

–50

75 100

4307 G04

PULLUPAC

–25

vs Temperature

VCC = 5.5V

VCC = 3.3V

25 50

0

TEMPERATURE (°C)

(ns)

PHL

t

950

900

850

(μA)

SD

I

800

750

100

75

4307 G02

700

–50

Input-Output High to Low
Propagation Delay vs C

130

CIN = 50pF

= R

R

120

110

100

90

80

70

60

PULLUPIN

0

PULLUPOUT

VCC = 5.5V

VCC = 3.3V

200 400 600 1000

C

(pF)

OUT

ISD vs Temperature

VCC = 5.5V

VCC = 3.3V

VCC = 2.3V

–25

OUT

= 10k

800

25 50

0

TEMPERATURE (°C)

4307 G07

100

75

4307 G02

onnection Circuitry

85

75

(mV)

IN

65

– V

OUT

V

55

45

2345

1

R

PULLUP

(kΩ)

–

IN

4307 G05

OUT

678910

Bus Stuck Low Timeout vs V

34

32

(ms)

30

TIMEOUT

t

28

26

2

2.5

3.5

3

VCC (V)

CC

4

4.5

5

5.5

4307 G06

4307f

5